The invention relates to a method for controlling provision of traffic informational data for updating traffic information.
So that the driver of a vehicle is informed about the status of traffic on a road, traffic informational data from a service provider may be made available. Traffic informational data may also be generated in the vehicle itself in that driving behavior on the route being driven is analyzed. Thus it may be detected, for instance, whether traffic information provided by a service provider is actually still valid on the route section being traveled. To attain improved quality of traffic information for vehicles, traffic data that have been generated in vehicles while a route is being traveled may be transferred to a control center. In the control center, the valid traffic information transferred from vehicles may be compared to the traffic status data available there and may be updated in to order broadcast improved traffic information.
Traffic data may be transmitted from the vehicles on a route section, for instance in the form of a so-called “string of pearls.” Strings of pearls include time series of geo-referenced positions, that is, each point has a time stamp that is made up of geographic lengths and widths obtained from GPS signals, and possibly information on link, direction of travel, and offset. In addition, vehicle-generated data with a highly expanded information spectrum may be generated and transferred. Data of this type are called XFCD (Extended Floating Car Data). In the control center, vehicle-generated data like XFCD may be linked to other data sources and used for generating updated traffic information
It is true that, for the purpose of updating, strings of pearls may be transferred continuously from every vehicle equipped with a transmitter device to a traffic service provider. However, permanent transfer of data from the vehicle is associated with direct and indirect costs. Among the direct costs are for instance the fees of mobile wireless providers. Indirect costs may be incurred when, for instance, a mobile wireless channel is overloaded and this leads to it not being possible to transmit important messages. In this case, different claims on communication would compete with one another.
However, it is also possible to generate traffic informational data in vehicles, with the transfer of this data to a central traffic service provider appearing entirely reasonable. For instance, if the traffic information of a service provider that is already present in the vehicle indicates a significantly longer travel time on a route section compared to ideal conditions and if, at the same time, while traveling the route section the vehicle determines a “no traffic jam” traffic status, the transfer of the newly-obtained traffic information in the vehicle to the traffic service provider might appear entirely reasonable. In this example, when the “no traffic jam” traffic status is determined, there are circumstances in which the transfer of a string of pearls nevertheless produces added value compared to non-transfer. Conversely, if there is a determination of a “traffic jam” traffic status in the vehicle, the transfer of a message might in some circumstances produce only minor added value, if for instance the traffic information of the traffic service provider that is already available results in a correct or nearly correct travel time.
It is desirable to provide a method for controlling provision of traffic informational data for updating traffic information in which the most recently acquired traffic informational data is not transferred to a traffic service provider of traffic information unless it has added value compared to the traffic informational data previously available from the service provider.
Claim 1 provides one embodiment of a method for controlling provision of traffic informational data for updating traffic information. The method for controlling provision of traffic informational data for updating traffic information may include the following acts:                Provision of first traffic informational data that on first route sections of a route represent a first traffic information status and of second traffic informational data that on second route sections of the route represent a second traffic information status, wherein the first traffic informational data represent a temporally older traffic information status than the second traffic informational data;        Determination of a plurality of first travel times for each of the first route sections as a function of the first informational data;        Determination of at least one characteristic value of a distribution of the first travel times for each first route section;        Determination of a plurality of second travel times for each of the second route sections as a function of the second traffic informational data;        Determination of at least one characteristic value of a distribution of the second travel times for each second route section;        Determination of a first time value for traffic information based on the first traffic informational data as a function of the determined characteristic value of a distribution of the first travel times, wherein the first time value represents a measure of the benefit of the first traffic informational data;        Determination of a second time value for another traffic information status based on a combination of the first traffic informational data and the second traffic informational data as a function of the determined characteristic value of a distribution of the second travel times, wherein the second time value represents measure for the benefit of the second traffic informational data;        Comparison of the first and second time values and provision of the second traffic informational data for updating the first traffic informational data as a function of the comparison of the first and second time values.        
With this given method, the added value that the transfer of the second traffic informational data, as currently determined in a vehicle, for updating the first traffic informational data already known by a traffic service provider would result in may be determined. The traffic informational data transmitted from the service provider to a vehicle may for instance include the estimated travel time for a route section and a characteristic value regarding the confidence of this estimate.
The method may be used both for controlling the transfer of data generated in the vehicle on established route sections and for controlling the transfer of data generated in the vehicle for variable traffic-adaptive route sections. In both application instances, initially a first time value is determined for traffic information that is based on the first traffic informational data. The first time value indicates a benefit that the initial traffic informational data have for a vehicle on a route section. Moreover, a second time value is determined for “updated” traffic information that is based on the first traffic informational data that has been updated with the second traffic informational data. The second time value thus provides a benefit that the “updated” traffic information would have for a vehicle on the route section. By comparing the two time values it is possible to determine a priority ratio that indicates whether the transfer of the second traffic informational data generated in the vehicle to a traffic service provider, for updating traffic information, represents an added value compared to traffic information that is already known.
The second traffic informational data are only transferred from the vehicle to the service provider if, for instance, the priority ratio exceeds a certain order of magnitude. Thus the method enables intelligent global control of the entirety of messages, in particular XFCD messages, in that the determined priority ratio is compared to a threshold value that is transferred, for instance, to a vehicle. Moreover, the method permits the efficiency of the benefit of available communication resources to be improved and ultimately permits the quality of the traffic information provided in a vehicle by a service provider to be improved.
A series of additional useful embodiments of the method shall be provided in the following.
In accordance with one possible embodiment of the method, an average speed may be calculated on each second route section when the section is traveled. The second traffic informational data may be provided for each second route section as a function of the average speed on that second route section, the length of that second route section, and a free speed on that second route section.
In accordance with another embodiment of the method, a plurality of travel times are determined for each second route section as a function of the second traffic informational data. The first and second time values may be determined as a function of the plurality of travel times determined for each second route section.
In accordance with another embodiment of the method, a free travel time may be determined on each second route section. The free travel time allocated to a second route section may be determined as a function of a length of that second route section and of the free travel speed allocated to that second route section. The first and second time values may be determined as a function of the free travel time determined for each second route section.
The method may be used in a first application instance, in which the first and second route sections are the same, because for instance the route sections are fixed and pre-defined. The method may also be used in a second application instance, in which the first and second route sections are different, because the sections are divided variably or in a traffic adaptive manner. Possible embodiments of the invention for the second application instance shall now be described in greater detail in the following.
In accordance with one possible embodiment of the invention, the second route sections may be defined on the route between a starting point and a target point in that the route is traveled and, between a begin point that is disposed between the starting point and the target point, and a traveled route position of the route, one of the second route sections is defined when a first traffic status between the begin point and the just traveled route position differs from an expected second traffic status between the route position and the target point. Thus, with respect to the just traveled route position, the second traffic status is thus investigated in a spatial window “upstream” of the most recently traveled route position.
In accordance with one useful embodiment of the method, the second route sections may be defined on the route between the starting point and the target point in that the starting point is established as begin position for one of the second route sections and when the route is traveled the following steps (a) through (e) are executed:
(a) Determination of an expected value of a first speed between the begin point and a traveled route position on the route;
(b) Determination of an average value of a second speed in a spatial range between the traveled route position and the target point;
(c) Comparison of the expected value of the first speed and the average value of the second speed;
(d) Establishment of an end point for the one section of the second route sections as a function of the comparison performed in step (c);
(e) Establishment of the one section of the second route sections between the begin point and the endpoint and definition of the end point as begin point for a second subsequent route section on the established second route section and repetition of steps (a) through (e) if the target point has not yet been traveled, and establishment of the one section of the second route sections between the begin point and the target point if the target point has already been traveled.
In accordance with another embodiment of the method, the second route sections are defined in that a standard deviation of the second speed in the spatial region between the traveled route position and the target point is determined and, as a function of the standard deviation, a limit is determined which, if exceeded, indicates a significant change in the traffic status. When the expected value for the first speed is compared to the average value of the second speed, now a difference between the expected value of the first speed and the average value of the second speed may be determined and compared to the limit.
In accordance with another embodiment of the method, a quantile is determined as characterizing value, wherein a median travel time may be determined as a quantile of a distribution of the first travel times on each of the first route sections. Virtual median travel times based on the first traffic informational data are allocated to the second route sections in that the median travel times for the first route sections are interpolated into the second route sections. The first time value may then be determined as a function of the virtual median travel time allocated to each second route section. Likewise, a median travel time may be determined as a quantile of a distribution of the second travel times on each of the second route sections. The second time value is then determined as a function of the median travel time allocated to each second route section.
The invention shall be explained in greater detail in the following using exemplary embodiments that are illustrated using the figures.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.